Uncertainties in Broadband Determination of the High-Frequency Spectral Decay, Kappa, in Eastern Canada
Bibliographic record
Abstract
ABSTRACT Kappa (the high-frequency spectral decay slope at near-source distances; often referred to as κ0) is determined at 25 seismograph stations in Eastern Canada using broadband ground-motion modeling approaches. The database comprises Fourier spectra (effective amplitude spectrum for the horizontal component and the vertical component, 0.8–40 Hz) computed from 3318 earthquakes of moment magnitude M 1.5–5 recorded on stations within 150 km. Average kappa values for bedrock sites, having shear-wave velocities from 850 to 2400 m/s, are highly variable, ranging from −29 to +21 ms (horizontal) and −28 to +11 ms (vertical), but appear on average to be near-zero. The values obtained are sensitive to methodology, especially the necessary adjustments to the spectra to account for site amplification effects. Kappa values do not appear to correlate well with site parameters such as rock shear-wave velocity, average shear-wave velocity in the upper 30 m, primary wave velocity, site class, type and age of rock, or instrument housing. This lack of correlation may reflect the noted sensitivities to methodological factors. We conclude that kappa values in rock environments are not reliably estimated from such proxies and should be determined from recorded ground motions at a given location. On average, there is little evidence of significant high-frequency attenuation on rock sites beyond that already accounted for in ground-motion modeling by the empirical parameterization of regional Q-related path effects.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".